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Direct Color -sensitive: The search for a direct color -sensitive color-sensitive medium continued. In 1891 Gabriel Lippmann, professor of physics at the Sorbonne, perfected his interference process, which relied upon the phenomenon that a thin film, such as oil upon water, will produce all the colors of the rainbow. The results were startling. Steichen in 1908 wrote Stieg-litz:
The eye has its greatest sensitivity in the green, is less sensitive to blue and violet, and is not at all sensitive to ultraviolet. This accounts for the fact that an average landscape photographs differently, with respect to tone values, than the eye sees it. In the average photograph of a landscape, the trees appear abnormally dark and the sky abnormally light. This is because light from the sky is especially rich in blue, violet, and ultraviolet, to all of which the film is particularly sensitive, and to which the eye is comparatively insensitive. On the other hand, trees reflect much green light, to which the eye is very sensitive and to which the film is much less sensitive.
After all these experiments, I believe that I am entitled to the conclusion that we are able to make bromide of silver sensitive to any color', it is only necessary to add to the bromide of silver a substance which absorbs the color in question, and which at the same time promotes the chemical decomposition of bromide of silver by light. |
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